CompressionConfig

Defined in: src/persistence/PersistenceOptions.ts:24

Compression directive — what algorithm a single write should use.

Properties

algorithm

readonly algorithm: CompressionAlgo

Defined in: src/persistence/PersistenceOptions.ts:25

---

level?

readonly optional level?: number

Defined in: src/persistence/PersistenceOptions.ts:44

Optional compression level — higher trades CPU for a smaller body. Algorithm-specific; out-of-range values are clamped, undefined uses the implementation default:

• gzip: 0–9 (default 6).
• zstd: 1–22 (default 3). Levels ≥20 (“ultra”) use large windows the pure-JS fzstd decompress-fallback may be unable to read (it caps at a 32 MB window) — keep ≤19 if any reader might run on a runtime without native zstd (i.e. not Bun and not Node ≥22.15).
• none: ignored.

The level is an encoder-only setting: it is NOT recorded on the wire (the body manifest stores the algorithm, not the level) and decompression never needs it. Changing the level therefore needs no migration — old bodies keep decoding, new bodies use the new level, and the two mix freely in one bucket.